=

#include<stdio.h>
int main()
{   int shi,fen;
int s,v,t;
scanf("%d %d",&s,&v);
t=s/v;
if(s%v!=0){
t++;}
if(t>470)
{
 shi=23-(t-470)/60;
}else{
    shi=7-(t-50)/60;
}
if(t%60>50)
{
    fen=60-(t%60-50);
}if(t%60<=50){
    fen=50-t%60;
}if(shi<10&&fen>=10){
printf("0%d:%d",shi,fen);
}if(shi<10&&fen<10){
printf("0%d:0%d",shi,fen);}
if(shi>=10&&fen<10){
    printf("%d:0%d",shi,fen);
}if(shi>=10&&fen>=10){
    printf("%d:%d",shi,fen);
}
return 0;
}